Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS5280727 A
Publication typeGrant
Application numberUS 07/786,388
Publication dateJan 25, 1994
Filing dateNov 1, 1991
Priority dateSep 11, 1987
Fee statusLapsed
Publication number07786388, 786388, US 5280727 A, US 5280727A, US-A-5280727, US5280727 A, US5280727A
InventorsPeter Hafner, Roland Unterseh
Original AssigneeEndress+Hauser Flowtec Ag
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electromagnetic flow measuring tube and method of making same
US 5280727 A
Abstract
An electromagnetic flow measuring tube is manufactured by forming an inner member which consists substantially of plastic and thereafter coating the inner member with a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member to form an outer member which surrounds the inner member in a form-stabilizing stiffening manner. Thus, when the inner member is formed from plastic in hot condition, as for instance by injection molding, it can cool down and solidify in a relaxed condition, so that it is free of intrinsic mechanical stresses when the outer member is applied. This eliminates the danger of a detachment of the inner member from the outer member and of subsequent occurrence of cracks in the material of the inner member. Mounting flanges, stiffening webs and other structural elements are integrally formed with the plastic inner member. This permits a simple and economic manufacture of flow measuring tubes having a complicated shape.
Images(3)
Previous page
Next page
Claims(33)
What is claimed is:
1. An electromagnetic flow measuring tube comprising an inner member formed substantially of plastic, the inner member having a tubular portion including an outer surface and an inner surface which defines a flow passage, an integrally formed mounting flange at each end of the tubular portion, and webs extending from the flanges to the outer surface of the tubular portion, the webs being formed integrally with the tubular portion and the flanges to stabilize the flanges and the tubular portion against deformation, the inner member including integrally formed electrode studs extending from the tubular portion at generally right angles to the axis of the flow passage, a bore formed in at least some of these electrode studs, and an electrode pressed into each of the bores, and an outer member consisting substantially of a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member and is directly applied to the inner member by means of a coating on the inner member which outer member surrounds the inner member to stabilize and strengthen the inner member.
2. The electromagnetic flow measuring tube according to claim 1 comprising electrically conductive layers applied on parts of the exterior surface of the inner tubular portion to form capacitive voltage collection electrodes and electrically insulating layers applied to at least a part of the electrically conductive layers.
3. The electromagnetic flow measuring tube according to claim 1 wherein the electrically insulating layers are provided with one or more cutouts in such a manner that the electrically conductive layers can be contacted from outside the outer member.
4. The electromagnetic flow measuring tube according to claim 1, further comprising pole shoes connected to magnetic cores, and means for coupling the pole shoes and the magnetic cores to the inner member.
5. The electromagnetic flow measuring tube according to claim 1 wherein the outer member is formed from electrically conductive material.
6. The electromagnetic flow measuring tube according to claim 5 wherein the material of the outer member is copper.
7. The electromagnetic flow measuring tube according to claim 1 wherein the inner member is formed by injection molding before the coating which forms the outer member is applied to the inner member.
8. The electromagnetic flow measuring tube according to claim 1 wherein the inner member is formed of fluoroplastic.
9. The electromagnetic flow measuring tube according to claim 1 wherein the inner member has a plurality of circumferential ribs formed on the outer surface of the tubular portion.
10. A flow measuring tube comprising:
an inner member formed substantially of a plastic material, the inner member being formed to include a tubular portion having an outer surface and an inner surface which defines a flow passage therethrough, a mounting flange formed integrally with the tubular portion at each end of the tubular portion, and web members extending from the flanges to the outer surface of the tubular portion, the web members being formed integrally with and from the same material as the tubular portion and the flanges, the inner member further including integrally formed electrode studs extending from the tubular portion transverse to a longitudinal axis of the flow passage, a bore formed in at least some of these electrode studs, and an electrode pressed into each of the bores; and
an outer member formed substantially of a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member, the outer member being applied to the inner member by means of a coating on the inner member which outer member surrounds the inner member to stabilize and strengthen the inner member.
11. The flow measuring tube of claim 10, further comprising electrically conductive layers applied on parts of the exterior surface of the inner tubular portion to form capacitive voltage collection electrodes, and electrically insulating layers applied to at least a part of the electrically conductive layers.
12. The flow measuring tube of claim 10, further comprising pole shoes coupled to magnetic cores, and means for coupling the pole shoes and magnetic cores to the inner member.
13. The flow measuring tube of claim 10, wherein the outer member is formed from electrically conductive material.
14. The flow measuring tube of claim 10, wherein the inner member is formed to include a plurality of circumferential ribs extending outwardly from the outer surface of the tubular portion.
15. A flow measuring tube comprising:
an inner member formed substantially of a plastic material to establish a general shape and geometric dimensions of the flow measuring tube, the inner member being formed to include a tubular portion having an outer surface and an inner surface which defines a flow passage therethrough and a mounting flange formed integrally with the tubular portion at each end of the tubular portion, the inner member further including integrally formed electrode studs extending from the tubular portion transverse to a longitudinal axis of the flow passage, a bore formed in at least some of these electrode studs, and an electrode pressed into each of the bores; and
a coating applied to the outer surface of the inner member after the inner member is formed, the coating conforming generally to the shape and geometric dimensions of the inner member to form an outer member which surrounds the inner member, the outer member being formed substantially of a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member to stabilize and strengthen the inner member.
16. The flow measuring tube of claim 15, wherein the inner member further comprises web members extending from the flanges to the outer surface of the tubular portion, the web members being formed integrally with and from the same material as the tubular portion and the first and second flanges to stabilize the flanges and the tubular portion against deformation.
17. The flow measuring tube of claim 15, further comprising electrically conductive layers applied on parts of the exterior surface of the inner tubular portion to form capacitive voltage collection electrodes, and electrically insulating layers applied to at least a part of the electrically conductive layers.
18. A flow measuring tube comprising:
an inner member formed substantially of a plastic material, the inner member formed to include a tubular portion having an outer surface and an inner surface which defines a flow passage therethrough, a mounting flange formed integrally with the tubular portion at each end of the tubular portion, and web members extending from the flanges to the outer surface of the tubular portion, the web members being formed integrally with and from the same material as the tubular portion and the flanges; and
an outer member formed substantially of an electrically conductive material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member, the outer member being applied to the inner member by means of a coating on the inner member which outer member surrounds the inner member to stabilize and strengthen the inner member.
19. The flow measuring tube of claim 18, wherein the inner member further includes integrally formed electrode studs extending from the tubular portion transverse to a longitudinal axis of the flow passage, a bore formed in at least some of these electrode studs, and an electrode pressed into each of the bores;
20. The flow measuring tube of claim 18, further comprising electrically conductive layers applied on parts of the exterior surface of the inner tubular portion to form capacitive voltage collection electrodes, and electrically insulating layers applied to at least a part of the electrically conductive layers.
21. The flow measuring tube of claim 18, further comprising pole shoes coupled to magnetic cores, and means for coupling the pole shoes and magnetic cores to the inner member.
22. The flow measuring tube of claim 18, wherein the inner member is formed to include a plurality of circumferential ribs extending outwardly from the outer surface of the tubular portion.
23. A flow measuring tube comprising:
an inner member formed substantially of a plastic material to establish a general shape and geometric dimensions of the flow measuring tube, the inner member being formed to include a tubular portion having an outer surface and an inner surface which defines a flow passage therethrough and a mounting flange formed integrally with the tubular portion at each end of the tubular portion;
a coating applied to the outer surface of the inner member after the inner member is formed, the coating conforming generally to the shape and geometric dimensions of the inner member to form an outer member which surrounds the inner member, the outer member being formed substantially of a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member to stabilize and strengthen the inner member;
electrically conductive layers applied on parts of the outer surface of the inner tubular portion to form capacitive voltage collection electrodes; and
electrically insulating layers applied to at least a part of the electrically conductive layers.
24. The flow measuring tube of claim 23, wherein the inner member further comprises web members extending from the flanges to the outer surface of the tubular portion, the web members being formed integrally with and from the same material as the tubular portion and the first and second flanges to stabilize the flanges and the tubular portion against deformation.
25. The flow measuring tube of claim 23, wherein the inner member further includes integrally formed electrode studs extending from the tubular portion transverse to a longitudinal axis of the flow passage, a bore formed in at least some of these electrode studs, and an electrode pressed into each of the bores.
26. An electromagnetic flow measuring tube comprising an inner member formed substantially of plastic, the inner member having a tubular portion including an outer surface and an inner surface which defines a flow passage, an integrally formed mounting flange at each end of the tubular portion, and webs extending from the flanges to the outer surface of the tubular portion, the webs being formed integrally with the tubular portion and the flanges to stabilize the flanges and the tubular portion against deformation, and an outer member consisting substantially of an electrically conductive material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member and is directly applied to the inner member by means of a coating on the inner member which outer member surrounds the inner member to stabilize and strengthen the inner member.
27. The flow measuring tube of claim 26, further comprising electrically conductive layers applied on parts of the exterior surface of the inner tubular portion to form capacitive voltage collection electrodes, and electrically insulating layers applied to at least a part of the electrically conductive layers.
28. The flow measuring tube of claim 27, wherein the electrically insulating layers are provided with one or more cutouts in such a manner that the electrically conductive layers can be contacted from outside the outer member.
29. The flow measuring tube of claim 26, further comprising pole shoes coupled to magnetic cores, and means for coupling the pole shoes and magnetic cores to the inner member.
30. The flow measuring tube of claim 26, wherein the material of the outer member is copper.
31. The flow measuring tube of claim 26, wherein the inner member is formed by injection molding before the coating which forms the outer member is applied to the inner member.
32. The flow measuring tube of claim 26, wherein inner member is formed of fluoroplastic.
33. The flow measuring tube of claim 26, wherein the inner member has a plurality of circumferential ribs formed on the outer surface of the tubular portion.
Description
BACKGROUND OF THE INVENTION

1. Introduction

This invention relates generally to electromagnetic flowmeters, and in particular to an electromagnetic flow measuring tube comprising an inner member formed substantially of plastic and an outer member which surrounds the inner member.

2. Description of the Prior Art

In an electromagnetic flowmeter, a magnetic field is generated in a flow measuring tube through which the fluid to be metered is conducted. The lines of flux of the magnetic field are perpendicular to the longitudinal axis of the flow measuring tube and to a transverse axis along which two electrodes are located at diametrically opposed positions. According to Faraday's law of induction, a voltage proportional to the flow velocity is induced in the fluid flowing through the flow measuring tube if the fluid is electrically conducting. This voltage is measured between the two electrodes and depends inter alia on the electrode spacing and the strength of the magnetic field. These two quantities are influenced by the geometrical dimensions of the flow measuring tube so that it is desired that the mechanical stability of the flow measuring tube be as high as possible.

As disclosed in U.S. Pat. No. 4,186,600, it is known for this purpose to provide a rigid tubular outer member, preferably a metal tube, the interior surface of which is coated with a plastic liner which is applied in a hot condition, usually by injection molding. The plastic liner serves to insulate the outer member from the electrically conducting fluid and also to protect it from damage if the fluid is chemically aggressive or corrosive. Compared with metals, plastic generally has a high thermal coefficient of expansion and low mechanical strength, in particular as regards tension, pressure and shearing. In the prior art flow measuring tubes of this kind, the plastic liner does not contribute to the mechanical stability of the flow measuring tube which is entirely provided by the rigid tubular outer member. If the flow meter is provided with mounting flanges, these are parts of the rigid tubular outer member.

When the plastic liner cools down after completion of the injection molding, the high thermal coefficient of expansion leads to a shrinkage of the plastic liner. This shrinkage can cause an at least partial detachment of the inner lining from the outer member and permanent mechanical stresses in the plastic. The detachments change the geometrical dimensions of the cross-section of the flow measuring tube, and this can lead to falsifications of the measuring voltage causing measuring errors. The mechanical stresses which are undissipated increase the risk of cracks occurring in the plastic.

It is known from U.S. Pat. No. 4,592,886 to fill the gaps formed by the detachments between the metal outer member and the plastic inner liner with a suitable material, for example a two-component epoxy, to insure in this manner the dimensional stability of the measuring tube cross-section. Introducing the filler into the intermediate spaces is however difficult. In addition, formation of a homogeneous internal cross-section is complicated.

SUMMARY OF THE INVENTION

An object of the invention is to provide a flow measuring tube which has a high dimensional stability but can be manufactured simply and economically.

It is a further object of the invention to provide a simple and economic method of making a flow measuring tube having a high dimensional stability.

The electromagnetic flow measuring tube according to the invention comprises an inner member formed substantially of plastic, the inner member having a tubular portion which defines a flow passage, an integrally formed mounting flange at each end of the tubular portion, and integrally formed flat stiffening webs extending from the flanges to the outer surface of the tubular portion, and an outer member consisting substantially of a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member and is directly applied to the inner member by means of a coating on the inner member which outer member surrounds the inner member in a form-stabilizing stiffening manner.

A preferred method of making the electromagnetic flow measuring tube according to the invention comprises the steps of forming an inner member which consists substantially of plastic, the inner member having a tubular portion which defines a flow passage, an integrally formed mounting flange at each end of the tubular portion and integrally formed flat stiffening webs extending from the flanges to the outer surface of the tubular portion, and thereafter applying to the inner member an outer member consisting substantially of a material which has a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member by means of a coating on the inner member, which outer member surrounds the inner member in a form-stabilizing stiffening manner and at least partially covers the exterior surface of the inner member.

The shape and the geometrical dimensions of the flow measuring tube according to the invention are determined by the inner member which is a separately formed plastic body. This plastic inner member also comprises the integrally formed mounting flanges, stiffening webs and other structural components that may be required, such as electrode studs. Since the outer member is applied to the inner member by means of a coating, it adopts the shape of the inner member however irregular this shape may be. This permits an easy and economic manufacture of electromagnetic flow measuring tubes of complicated shapes.

An important advantage of the flow measuring tube according to the invention and the method of manufacturing it results from the fact that the formation of the inner member is completed before the outer member is applied. Thus, when the inner member is formed from plastic in hot condition, as for instance by injection molding, it can cool down and solidify in a relaxed condition, so that it is free of intrinsic mechanical stresses when the outer member is applied. This eliminates the danger of a detachment of the inner member from the outer member and of subsequent occurrence of cracks in the material of the inner member. The subsequent application of the outer member does not cause any appreciable deformation of the cross-section of the inner member or stresses in the material of the inner member.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention as well as other objects and further features thereof, reference is made to the following description to be read in conjunction with the drawings, wherein

FIG. 1 shows a prior art electromagnetic flowmeter;

FIG. 2 is a plan view of an electromagnetic flow measuring tube in accordance with the invention;

FIG. 3 is a section taken through the electromagnetic flow measuring tube shown in FIG. 2 on the plane indicated by line III--III therein;

FIG. 4 is a section taken through the electromagnetic flow measuring tube on the plane indicated by line IV--IV in FIG. 3;

FIG. 5 is a section taken through a part of another electromagnetic flow measuring tube in accordance with the invention on the plane indicated by line V--V in FIG. 6; and

FIG. 6 is a section taken through the part of the electromagnetic flow measuring tube shown in FIG. 5 on the plane indicated by line VI--VI therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The prior art electromagnetic flowmeter shown in FIG. 1 comprises a measuring tube 1 through which an electrically conductive liquid to be metered flows with a velocity v. Two exciting coils 2 and 3 through which an alternating current or a pulsating DC current I flows generate in the interior of the measuring tube 1 a magnetic field B perpendicular to the longitudinal axis of the measuring tube 1. According to the well-known principles of electromagnetic flowmeters which are based on Faraday's law of induction an electric voltage proportional to the flow velocity v is induced in the flowing liquid. The induced voltage is measured between two electrodes 4 and 5 located at diametrically opposed positions along a transverse axis which is perpendicular both to the longitudinal axis of the measuring tube 1 and to the direction of the magnetic field B. The electrodes 4 and 5 can be in electric contact with the liquid for conductive collection of the induced voltage, or they can be electrically insulated from the liquid for capacitive collection of the induced voltage.

The measuring tube 1 comprises a stainless steel tube 7 which is provided with a plastic inner lining 6. The function of the inner lining 6 is to insulate the stainless steel tube 7 from the electrically conductive liquid.

FIGS. 2 to 4 show a first embodiment of a measuring tube 10 made according to the invention. The shape and structure of the measuring tube will be apparent from the following description of the method by which it is manufactured.

First, an inner member 11 is formed as a solid body of plastic material. This is preferably done by injection molding. The greater part of the inner member 11 is formed by a thick-walled tubular portion 12 having an axial flow channel 13. At each end of the tubular portion 12 a mounting flange 14, 15 is integrally formed with the tubular portion 12 from the plastic material. Flat stiffening webs 16 and 17 of triangular shape are integrally formed with the tubular portion 12 and the flange 14 in a common plane at diametrically opposed positions, the outer edges of the webs 16 and 17 extending from the periphery of the flange 14 to the outer surface of the tubular portion 12. Likewise, flat stiffening webs 18 and 19 of triangular shape are integrally formed with the tubular portion 12 and the flange 15 at diametrically opposed positions in the same plane as the webs 16 and 17, the outer edges of the webs 18 and 19 extending from the periphery of the flange 15 to the outer surface of the tubular portion 12.

In the middle of the tubular portion 12 two electrode studs 20 and 21 are formed integrally with the tubular portion from the plastic material. The electrode studs 20 and 21 extend radially from the tubular portion 12 at diametrically opposed positions in the same plane as the webs 16 to 19. Further electrode studs 22, 23 and 24 are formed integrally with the tubular portion 12 from the plastic material in the vicinity of the flanges 14 and 15, respectively, the electrode studs 22 to 24 extending radially from the tubular portion 12 in a plane which is normal to the plane of the electrode studs 20 and 21.

A plurality of circumferential ribs 25 is integrally formed on the outside of the tubular portion 12 in the regions situated between the electrode studs 20, 21 and the flanges 14, 15, respectively.

After the formation of the inner member 11 in the before-described manner, pole shoes 26 and 27 connected to magnetic cores 28 and 29, respectively, are attached to the outside of the tubular portion 12 in the middle thereof between the flanges 14 and 15 at diametrically opposed positions so that the cores 28 and 29 extend radially from the tubular portion 12 in a plane which is normal to the plane of the electode studs 20 and 21. Preferably the pole shoes 26 and 27 are placed in corresponding recesses formed in the outer surface of the tubular portion 12. The pole shoes with the attached cores can be held in place by any suitable means during the following manufacturing step, for instance by fixing pins extending into corresponding holes provided in the inner member 11, or by external holding means.

In the next manufacturing step the exterior surfaces of the inner member 11 and of the pole shoes 26, 27 are directly coated with a material having a lower coefficient of thermal expansion and a higher mechanical strength than the material of the inner member 11 to form an outer member 30 which surrounds the inner member 11 in a form-stabilizing stiffening manner. As coating material preferably a non-ferromagnetic metal is used, in particular copper. The coating can be done by any one of the known coating methods, in particular electroplating, chemical deposition or one of the thermal spraying methods, such as plasma spraying or flame spraying. Preferred materials for the inner member 11 are fluoroplastics, for example Teflon (PTFE, polytetrafluoroethylene) or Hostaflon (ETFE, ethylene tetrafluoroethylene) which can particularly well be coated with copper.

If certain parts of the measuring tube 10 are not to be covered by the outer member 30, this can be achieved either by covering these parts with suitable masks during the coating process or by locally removing the coating material from these parts after the coating. In the embodiment of FIGS. 2 to 4, for instance, the end faces of the flanges 14 and 15, the end faces of the electrode studs 20 and 21, and the magnetic cores 28 and 29 are not covered with the coating material of the outer member. Preferably, the magnetic cores 28 and 29 are covered with removable sleeves, and the end faces of the flanges 14 and 15 with covering plates during the coating process. The coating material on the end faces of the electrode studs 20 and 21 may be removed after the coating, and in the same step a separation may be provided between the coating material on the circumferential surfaces of the electrode studs 20, 21 and the coating material on the tubular portion 12 so that shield sleeves 31 and 32 are formed on the electrode studs.

For finishing the measuring tube 10, bores are provided in the electrode studs 20 to 24, as required, and pin-shaped electrodes are pressed into these bores In the upper half of FIG. 3 a measuring electrode 33 is shown which is pressed in a bore provided in the electrode stud 20. A second measuring electrode will be pressed in a bore that will be provided in the electrode stud 21. Two further electrodes can be mounted in the same manner in the electrode studs 23 and 24 which can be used for applying a desired potential, such as mass potential. A further electrode mounted in the electrode stud 22 can, for instance, be used to determine whether the liquid contains air bubbles or whether the measuring tube is completely filled with the liquid, provided that the measuring tube is installed in the position shown in FIG. 2 where the electrode stud 22 extends vertically upwards. If such additional electrodes are to be provided it is, of course, necessary to remove the coating material from the end faces of the electrode studs in order to avoid a short-circuiting of the electrodes if the coating material is electrically conductive.

Finally, exciting coils 34 and 35 are mounted on the magnetic cores 28 and 29, respectively.

With the coating method a firm bonding of the outer member 30 on the plastic inner member 11 is achieved. The inner member can cool down and relax freely after it has been formed and before the material of the outer member is applied so that the inner member is free of inherent mechanical stresses when the outer member is applied by coating. This largely eliminates the probability of a subsequent occurrence of cracks in the material of the inner member. The application of the outer member by coating does not lead to any appreciable deformation of the inner member.

A further advantage of the coating method is that the outer member can be made up of layers of different materials. This is done for example by means of different electroplating baths. Thus, at first a bonding layer can be applied of a material which adheres particularly firmly to the plastic material of the inner member, and then one or more further layers can be applied on the bonding layer to provide the desired form-stabilizing and stiffening effect.

By the use of masks during the coating steps regions of different properties can be provided in the outer member. For instance, by applying layers of different materials regions of different conductivity can be produced in order to prevent eddy currents. Moreover, it is possible to create functional components of the flowmeter, such as electrodes, by taking advantage of the various possibilities of the coating method.

Referring to FIGS. 5 and 6, a modified embodiment of the invention is illustrated in order to explain how the coating method used for the production of the outer member can be utilized for making measuring electrodes for capacitive collection of the induced voltage. FIG. 5 is a partially sectioned plan view along the line V--V of FIG. 6 of that part of the measuring tube which contains one of the two measuring electrodes, and FIG. 6 is an enlarged sectional view, not true to scale, along the line VI--VI of FIG. 5. The other measuring electrode is, of course, identical to the one shown in FIGS. 5 and 6 and will, therefore, not be described.

FIGS. 5 and 6 show a portion of the inner member 41 of the measuring tube which may be manufactured in the same way as the inner member 11 of FIGS. 2 to 4, but without the electrode studs for the measuring electrodes. The measuring electrode 42 is formed prior to the formation of the outer member by coating steps which are compatible with the coating method used for forming the outer member. A first electrically conductive layer 43 (indicated in dotted lines in FIG. 5) is applied onto a portion of the surface of the inner member 41. In operation, this first conductive layer 43 forms one plate of a capacitor, of which the dielectric is the non-conducting material of the inner member 41 and the other plate is the electrically conductive fluid which flows in the direction of the arrow of FIG. 5 through the measuring tube.

The first conductive layer 43 is then at least partially coated with a first electrically insulating layer 44 which in turn is at least partially coated with a second electrically conductive layer 45 to form a shield electrode in particular against stray capacitances. The layer 45 is expediently connected to ground or earth potential which can be done via a further conductive layer, not shown. If the material of the outer member is electrically conductive, for instance copper, the second conductive layer is coated with a second electrically insulating layer 46. The extent of the two insulating layers 44 and 46 can optionally be limited to the regions of the first and second conductive layers 43 and 45, respectively, or cover the entire outer surface of the inner member 41. Finally, the outer member 47 is formed by coating the outer surface of the inner member 41 and the structure formed by the layers 43 to 46 with one or more layers, as described before with reference to the embodiment of FIGS. 2 to 4.

In the specific embodiment of FIGS. 5 and 6 the insulating layer 44, the conductive layer 45, the insulating layer 46 and the outer member 47 comprise aligned cutouts which together form an opening 48 leading to the first conductive layer 43. This makes it possible to contact in a simple manner the first conductive layer 43, which ist the active part of the measuring electrode 42, from outside the outer member 47.

The layers of the second measuring electrode are formed simultaneously with the corresponding layers 43 to 46 of the first measuring electrod by the same process steps. If desired, further electrically conductive and insulating layers may simultaneously be applied on the inner member 41 for other purposes, for instance to form electrodes at the places of the electrode studs 22, 23 and/or 24 of the embodiment of FIGS. 2 to 4.

The embodiment of FIGS. 5 and 6 shows that the production method according to the invention is particularly suitable for measuring tubes with capacitive electrodes because the structure of capacitive electrodes is formed essentially by layers covering each other (dielectric, capacitor plate, insulation, shield electrode, etc.) and such layers can conveniently be applied in the course of the method used for manufacturing the measuring tube according to the invention.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2898228 *Feb 18, 1957Aug 4, 1959Du PontMethod for coating polyfluoroethylenes
US3009101 *May 5, 1959Nov 14, 1961Zellweger Uster AgDevice for determining spontaneous cross sectional variations in textile materials
US3039051 *Jul 18, 1960Jun 12, 1962Zellweger Uster AgApparatus for gaging textile materials
US3286522 *Aug 13, 1963Nov 22, 1966Cushing Vincent JMagnetoelectric flowmeter apparatus
US3294059 *Apr 15, 1963Dec 27, 1966Barnes Charles RDeposition of nickel films on the interior surface of polytetrafluoroethylene tubing
US3465585 *May 25, 1967Sep 9, 1969Tokyo Shibaura Electric CoFlow detection signal generator for electromagnetic flowmeters
US3664191 *Jun 1, 1970May 23, 1972Fischer & Porter CoExplosion-proof self-cleaning electrodes
US3709727 *Apr 30, 1971Jan 9, 1973Hooker Chemical CorpMetalizing substrates
US3824856 *Jan 22, 1973Jul 23, 1974Fischer & Porter CoHigh-pressure electromagnetic flowmeter
US3959723 *Sep 13, 1974May 25, 1976Wagner Delmer WLumber moisture measurement apparatus which is less sensitive to lumber movement and spacing
US4002996 *Jun 18, 1975Jan 11, 1977Elkay Electronics Ltd.Level detector using oscillator circuit with two capacitive probes
US4186600 *Oct 3, 1978Feb 5, 1980Fischer & Porter Co.Magnet system for electromagnetic flowmeter
US4329879 *Jul 14, 1980May 18, 1982Fischer & Porter Co.Insulating liner for electromagnetic flowmeter tube
US4337279 *Jan 23, 1981Jun 29, 1982Uop Inc.Method for increasing the peel strength of metal-clad polymers
US4403933 *Apr 14, 1982Sep 13, 1983Fischer & Porter CompanyApparatus for injection-molding a liner onto a metal spool
US4539853 *Jun 27, 1984Sep 10, 1985Fischer & Porter CompanyMagnetic flowmeter
US4557957 *Mar 18, 1983Dec 10, 1985W. L. Gore & Associates, Inc.Microporous metal-plated polytetrafluoroethylene articles and method of manufacture
US4567775 *Sep 28, 1984Feb 4, 1986Fischer & Porter Co.Flangeless, compact, leakproof over wide temperasture and pressurerange
US4592886 *Apr 28, 1982Jun 3, 1986Fischer & PorterTechnique for stabilizing injection molded flowmeter liner
US4614121 *Jan 14, 1985Sep 30, 1986Danfoss A/SElectromagnetic flow meter
US4631969 *Aug 5, 1985Dec 30, 1986Fischer & Porter CompanyCapacitance-type electrode assemblies for electromagnetic flowmeter
US4658652 *Feb 14, 1986Apr 21, 1987Fischer & Porter Co.Electromagnetic flowmeter with capacitance type electrodes
US4752727 *Aug 15, 1985Jun 21, 1988Endress U. Hauser Gmbh U. Co.Arrangement for detecting spatial inhomogeneities in a dielectric
US4782282 *Jul 9, 1986Nov 1, 1988Dickey-John CorporationCapacitive-type seed sensor for a planter monitor
AU214349A * Title not available
DE1773484A1 *May 22, 1968Nov 18, 1971Eckardt Ag JMagnetische Durchflussmesseinrichtung
DE1924152A1 *May 12, 1969Nov 20, 1969Shell Int ResearchVerfahren zum Abtrennen eines Bestandteils aus einem fluessigen Gemisch
DE2030263A1 *Jun 19, 1970Dec 23, 1971Heinrichs Messgeraete JosefFlowmeter pipe - with thick-walled ptfe lining
DE3011510A1 *Mar 25, 1980Oct 15, 1981Fischer & Porter GmbhInduktive durchflussmesseinrichtung
DE3201562A1 *Jan 20, 1982Aug 18, 1983Turbo Werk Messtechnik GmbhInductive flow meter
DE3313448A1 *Apr 13, 1983Oct 20, 1983Fischer & Porter CoVorrichtung und verfahren zum spritzen einer isolierenden buchse auf einem spulenkoerper
DE3340103A1 *Nov 5, 1983May 23, 1985Krohne Messtechnik KgMeasuring sensor for magnetoinductive flow meters
EP0142048A2 *Oct 12, 1984May 22, 1985Fischer & Porter GmbHInductive flow meter
SU187344A1 * Title not available
Non-Patent Citations
Reference
1Barrett et al., "The Principles of Engineering Materials", Prentice-Hall, Inc., 1973, pp. 34, 35.
2 *Barrett et al., The Principles of Engineering Materials , Prentice Hall, Inc., 1973, pp. 34, 35.
3 *Chemical Engineers Handbook, 5th ed., Perry and Chilton, eds., McGraw Hill Book Co., New York.
4Chemical Engineers' Handbook, 5th ed., Perry and Chilton, eds., McGraw-Hill Book Co., New York.
5Clauser, "Industrial and Engineering Materials", McGraw-Hill Book Company, 1975, pp. 46, 47, 174, 189.
6 *Clauser, Industrial and Engineering Materials , McGraw Hill Book Company, 1975, pp. 46, 47, 174, 189.
7 *Kirk Othmer, Encyclopedia of Chemical Technology , John Wiley & Sons, vol. 15, 1981, pp. 253 257.
8Kirk-Othmer, "Encyclopedia of Chemical Technology", John Wiley & Sons, vol. 15, 1981, pp. 253-257.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5817948 *Jan 21, 1997Oct 6, 1998Elsag International N.V.Electromagnetic flowmeter with non-protruding contacting electrodes and method for producing the same
US5925830 *Sep 11, 1996Jul 20, 1999Georg Fischer Rohrleitungssysteme AgElectromagnetic flowmeter construction
US6595069 *Nov 28, 2001Jul 22, 2003Endress + Hauser Flowtec AgElectromagnetic flow sensor including insulating material and embedded reinforcing body
US6658720 *Mar 13, 2000Dec 9, 2003Endress + Hauser Flowtec AgMethod of manufacturing an electromagnetic flow sensor
US6877386 *Feb 26, 2003Apr 12, 2005Siemens Flow Instruments A/SInsert for a measuring tube of an inductive flowmeter
US6990726Jun 17, 2003Jan 31, 2006Endress + Hauser Flowtec AgMethod of manufacturing an electromagnetic flow sensor
US7155983 *Feb 4, 2005Jan 2, 2007Entegris, Inc.Magnetic flow meter with unibody construction and conductive polymer electrodes
US7261001Dec 1, 2005Aug 28, 2007Krohne AgMagnetoinductive flowmeter and method for producing a magnetoinductive flowmeter
US7343817May 31, 2007Mar 18, 2008Entegris, Inc.Magnetic flow meter with unibody construction and conductive polymer electrodes
US7380468 *Dec 20, 2002Jun 3, 2008Schlumberger Technology CorporationDevice for integrating electrodes characterizing the flow of a multiphase fluid in a tubing
US7444885 *Dec 21, 2006Nov 4, 2008Abb Patent GmbhVortex flow measuring instrument
US7552651 *Jul 13, 2006Jun 30, 2009Yokogawa Electric CorporationElectromagnetic flowmeter having a lining member locked in the vicinity of the core
US7930816 *Feb 18, 2005Apr 26, 2011Abb LimitedMethods for manufacturing flow meter insert
US8127622 *Mar 23, 2009Mar 6, 2012Smc Kabushiki KaishaElectromagnetic flowmeter having a detachable measuring tune from the body
US8245580Oct 2, 2009Aug 21, 2012Rosemount Inc.Compliant coil form
US8286503 *Nov 17, 2009Oct 16, 2012Krohne AgElectromagnetic flowmeter having a measuring tube with varying cross section and wall thickness
US8448524Dec 12, 2011May 28, 2013Sensus Usa Inc.Magnetic inductive flow meter
US8615872 *Aug 18, 2009Dec 31, 2013Abb Technology AgMethod of manufacturing a flow measurement device
US20100037452 *Aug 18, 2009Feb 18, 2010Abb Technology AgFlow measurement device
US20100126282 *Nov 17, 2009May 27, 2010Krohne AgElectromagnetic flowmeter
CN101738229BNov 17, 2009Jun 11, 2014克洛纳有限公司磁感应的流量测量仪
DE102007037166A1Aug 7, 2007Feb 19, 2009Endress + Hauser Flowtec AgMeßgerät
DE102008057756A1 *Nov 17, 2008May 27, 2010Krohne AgMagnetisch-induktives Durchflußmeßgerät
DE102011006731A1Apr 4, 2011Oct 4, 2012Endress + Hauser Flowtec AgVerfahren zur Herstellung eines Kunststoffs für eine Auskleidung eines Messrohrs eines Durchflussmessgeräts
EP1666849A1 *Oct 14, 2005Jun 7, 2006Krohne AGElectro-magnetic flowmeter and method for its manufacture
EP1846733A2 *Feb 2, 2006Oct 24, 2007Entegris, Inc.Magnetic flow meter with unibody construction and conductive polymer electrodes
EP2187180A2 *Nov 3, 2009May 19, 2010Krohne AGMagnetic-inductive flow measuring apparatus
WO2006084061A2 *Feb 2, 2006Aug 10, 2006Chinnock Robert TMagnetic flow meter with unibody construction and conductive polymer electrodes
WO2010142450A1 *Jun 11, 2010Dec 16, 2010Sensus Metering SystemsMagnetic-inductive flow meter
WO2012136456A1Mar 15, 2012Oct 11, 2012Endress+Hauser Flowtec AgMethod for producing a plastic for a lining of a measurement tube of a flow meter
Classifications
U.S. Classification73/861.12, 73/861.11
International ClassificationG01F1/58
Cooperative ClassificationG01F1/58, G01F1/584
European ClassificationG01F1/58, G01F1/58B
Legal Events
DateCodeEventDescription
Apr 2, 2002FPExpired due to failure to pay maintenance fee
Effective date: 20020125
Jan 25, 2002LAPSLapse for failure to pay maintenance fees
Aug 21, 2001REMIMaintenance fee reminder mailed
Mar 18, 1997FPAYFee payment
Year of fee payment: 4
Jul 19, 1994CCCertificate of correction
Aug 24, 1992ASAssignment
Owner name: ENDRESS + HAUSER FLOWTEC AG A SWISS CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:FLOWTEC AG, A SWISS CORP.;REEL/FRAME:006236/0842
Effective date: 19911122
Dec 20, 1991ASAssignment
Owner name: FLOWTEC AG A CORP. OF SWITZERLAND, SWITZERLAND
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:HAFNER, PETER;UNTERSEH, ROLAND;REEL/FRAME:005947/0897
Effective date: 19911206